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It is a known phenomenon that some cultivars or even all
cultivars of a certain species or grex breed only one way - some as pod parents
only, others as pod parents only. The reason for this is unknown. The most
striking example I know of is Onc. leucochilum. It breed very well as a pollen
parent but is un utterly failure as pod parent (except for sib crosses). Bob
Dugger, Goodale Moir and myself have made - literally - hundreds of attemps to
use Onc. leucochilum as a pod parent and failed. If you see a cross with Onc.
leucochilum listed as a pod parent, the listing is wrong. Perhaps the same is
true for B. cucullata (at least in conjunction with Hsgwa.).
Generally speaking, complex hybrids - usually - have a
better succes rate in making crosses. It seems that species have a built-in
mechanism by which pollen form other species is almost always rejected. There
are comparatively few natural hybrids, except when a species is in the process
of 'falling apart' into newly emerging species. As an example see Odm. crispum
and its numerous natural hybrids (that were usually labeled 'Odm. crispum'). In
hybrids that are not too advanced this mechanism of rejecting pollen from other
species/hybrids seem to be often reduced. However there are examples where this
is not true. One of them is Aliceara (Brs x Milt x Onc) whose pollen rarely ever
works. In fact I beleive that a cross listing an Alcra. as pollen parent, then
either the cross or the 'Alcra' is misnomed.
Helmut Rohrl, La Jolla (sunny S. Calif.)
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